Renal function tests, Acid base, renal stones Flashcards
Hierarchy of kidney function tests
- Direct GFR measurements
- Used in research - eGFR estimated from serum creatinine
(CKD-EPI) - Serum creatinine
- 24 hr Creatinine clearance
- Serum urea.
Diabetic ketoacidosis metabolic consequences
- Fluid
- Filtration
- Ions
Loss of fluid via urine to to hyperglycaemia= decreased blood flow to kidney
Decrease glomerular filtration= decreased eGFR
Increased urea and creatinine
Increased serum K due to decreased renal excretion
Potassium and diabetic ketoacidosis
To balance pH, extracellular H+ from blood is exchanged for intracellular K+
- Decreases renal excretion of K+
High serum K+ but low body K+
- As K+ has moved out of cells
Causes of anion gap
Glycols
Oxoproline
L-Lactate
D-Lactate
Methanol
Aspirin
Renal failure
Ketoacidosis
Na and DKA
Bicarbonate is co-transported with Na into blood to buffer
- Causes water retention= AKI
Water is lost via osmotic diuresis
- Polydipsia
Acute renal injury
- Defintion
- Causes
- Complications
Abrupt loss in renal function within 7 days.
- Increased serum creatinine
- Decreased urine production
Causes
- Prerenal: shock, stenosis, obstruction
- Renal: drugs,
- Post renal: Urinary retention, stones.
Complications
- Hyperkalemia
- Acidosis
- Hyperphosphatemia
- Fluid overload
Acute renal injury
- Assessment
Volume status
- Fluid overload
- Dehydration
Electrolytes
- Bicarb, phosphate, Ca, K, Mg
FBC
Uric acid, albumin
Albuminuria
- Significance
- Assessment
Indication of glomerular filtration
- Increased albumin= poor filtration
Assessment: Urinanalysis
- ACR: urine concentration accounted for.
CKD stages
According to eGFR
1- Normal= >90
2= 60-89
3a= 45-59
3b= 30-44
4= 15-29
5= <15
Albuminuria stages
- Normal
- Microalbuminuria
- Macroalbuminuria
Urine ACR mg/mmol
Normal
- Male <2.5
- Female <3.5
Micro
- Male 2.5-25
- Female 3.5-35
Macro
- Male >25
- Female >35
Nephrotic syndrome metabolic consequences
- Proteinuria due to glomerular dysfunction
- Low serum albumin due to renal loss
- increases liver albumin + lipoprotein synthesis= hyperlipidaemia
- increase in clotting factors= thrombotic disease - Low oncotic pressure= peripheral oedema
Nephrotic syndrome diagnosis
Albuminuria
- ACR> 250 mg/mmol
- Increased ACR> 70mg/mmol= 1g protein/ 24 hr
Low serum albumin
- <30g/L
Peripheral oedema
Urea production
Protein broken down to amino acids–> Metabolised to urea.
- Alanine–>(ALT) Urea + pyruvate
- Aspatate —> (AST) Urea+ Oxaloacetate
Creatinine production
Waste product creatine-phosphate in breakdown muscle-
Creatine kinase
Enzyme that converts creatine to Phosphocreatine
Clinical
- Increase with muscle mass
- Increases after physical exertion
- Indication of rapid muscle breakdown: rhabdo, AKI, MI.
